#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

int main()
{
    extern char** environ;
    
    for (int i = 0; environ[i]; ++i)
        printf("%d : %s\n", i, environ[i]);

    printf("%s : %s\n", "PWD", getenv("PWD"));
    printf("%s : %s\n", "USER", getenv("USER"));

    return 0;
}
